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So, although increasing the incoming neutron energy reduces the energy resolution, thermal NSE would still offer an energy resolution in the microelectronvolt range for large energy and momentum transfers. However, the energy resolution of NSE does depend on the wavelength used for the measurement. In NSE, the resolution is not coupled to Δλ/λ since the energy information is encoded in the Larmor precession of the neutron spin (Mezei, 1972 ▸). This leads to a reduction of Q-space coverage and neutron flux.

Increasing the resolution can be achieved by decreasing the incoming neutron energy and/or Δλ/λ. In comparison with conventional inelastic neutron scattering (INS) techniques such as time-of-flight or triple-axis spectroscopy (TAS), neutron spin-echo (NSE) spectroscopy offers several key advantages.įirst, in classical INS the energy resolution is strongly coupled to the incoming neutron energy and the width of the wavelength band Δλ/λ.

For instance, CAMEA, a modern spectrometer of this type, has recently started operation at the Paul Scherrer Institute (Groitl et al., 2016 ▸ Janas et al., 2021 ▸ Allenspach et al., 2021 ▸). The importance of these questions has been addressed in terms of the development of multi-analyzer spectrometers at various beamlines worldwide. Similarly, the diffusion in ionic liquids and solvent-based electrolytes has been attracting great interest (Lundin et al., 2021 ▸ Burankova et al., 2018 ▸ Adya et al., 2007 ▸ Osti et al., 2019 ▸). Since many batteries rely on ion exchange and/or the ionic conductivity of lithium and hydrogen, determination of diffusion mechanisms in these materials is essential in understanding and improving this performance (Hester et al., 2016 ▸ Kuznetsov et al., 2021 ▸ Li et al., 2021 ▸ Klein et al., 2021 ▸ Okuchi et al., 2018 ▸). Another major field of research where such instrumentation is required concerns hydrogen- or lithium-based functionalities in solids. For instance, such high-resolution spectroscopy over a large dynamic range promises unambiguous identification of quantum-spin liquids (Paddison et al., 2017 ▸ Shen et al., 2016 ▸), where knowledge of spectral details such as the existence of tiny gaps and the structure of the low-lying modes is key. In magnetic materials this includes spin-frozen states in classical spin glasses and highly correlated spin states in geometrically frustrated systems (Musgraves et al., 2019 ▸). Key scientific questions that require high energy resolution over a large Q range involve, for example, the investigation of ground states without long-range order or well defined excitations. The need for high-resolution neutron spectroscopy over a wide range of momentum transfers, Q, has motivated major advances in neutron instrumentation in recent years. To illustrate the feasibility of TIGER, this paper presents the details of its implementation at the RESEDA beamline at FRM II by means of an additional velocity selector, polarizer and analyzer. In turn, the thermal MIEZE option for greater ranges (TIGER) closes the gap between classical neutron spin-echo spectroscopy and conventional high-resolution neutron spectroscopy techniques such as triple-axis, time-of-flight and back-scattering. The use of thermal neutrons increases the range of validity of the spin-echo approximation towards shorter spin-echo times. The second advantage is that multi-analyzer setups can be implemented with comparatively little effort. This allows for the study of spin fluctuations in ferromagnets, and facilitates the study of samples with strong spin-incoherent scattering. The first is the possibility to investigate spin-depolarizing samples or samples in strong magnetic fields without loss of signal amplitude and intensity. MIEZE has two prominent advantages compared with classical neutron spin echo. A modulation of intensity with zero effort (MIEZE) setup is proposed for high-resolution neutron spectroscopy at momentum transfers up to 3 Å −1, energy transfers up to 20 meV and an energy resolution in the microelectronvolt range using both thermal and cold neutrons.